Recently, there are rapidly increasing demands for a LED lighting apparatus of a high power and high efficiency. According to the demands, a direct input AC powered LED lighting continues to be developed and released.
Generally, in a direct input AC powered LED lighting, a flickering of LEDs occurs due to characteristics of AC drive circuit. To reduce or eliminate the flickering of LEDs, capacitors were connected to the LED drive circuit. U.S. Pat. No. 9,532,412 discloses an example of such a direct input AC powered LED lighting system.
According to disclosure of the US patent, capacitors as anti-flickers protrude from a front surface of the substrate of LED module as the capacitors are mounted on the substrate. The protrusion of capacitors from the front surface obstructs physical contact between the rear surface of the substrate and a heat-sink, and thus it results in diminishing the efficiency of heat dissipation at the heat sink. In addition, the protrusion of capacitors from the front surface of the substrate blocks light of LEDs and thus forms a dead zone or a shading zone behind the capacitors.
Recently, it requires that a lighting device on a ceiling should comply with ‘UL 5VA flammability Standard’. However, even though there were many trials to upgrade material of components, they fail to provide with substantially effective results.